Control device and recording medium encoded with program

ABSTRACT

A control device which controls a machine tool so as to move a table during exchange of tools includes: a movement distance acquisition unit which acquires a movement distance of the table during tool exchange; a movement time calculation unit which calculates a fastest movement time from an acquired movement distance, and a speed at which the table is caused to move fastest; a tool exchange time calculation unit which calculates a tool exchange time; a comparison unit which compares the tool exchange time calculated with the fastest movement time calculated; and a speed changing unit which changes the movement speed of the table, in a case of the fastest movement time being shorter than the tool exchange time, so that the movement time of the table becomes longer than the fastest movement time.

This application is based on and claims the benefit of priority fromJapanese Patent Application 2019-222314, filed on 9 Dec. 2019, thecontent of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a control device and a recordingmedium encoded with a program.

Related Art

Conventionally, a machine tool has been known which machines a workpieceplaced on a table using a tool. In the machine tool, the tool and thetable are moved to machine a workpiece into a predetermined shape. Thecontrol device controls the movement of the machine tool.

Shortening of the cycle time for machining is important for the machinetool. Therefore, the speed of the movement of the table, exchange oftools, etc. is often set so as to be the fastest. For example, a toolholder which shortens the tool exchange time has been proposed (forexample, refer to Patent Document 1).

Patent Document 1: Japanese. Unexamined Utility Model Application,Publication No. S62-153029

SUMMARY OF THE INVENTION

In relation to shortening of the cycle time, for example, it is usefulto move the table in advance to the next machining position whileexchanging tools. After exchanging tools, it is thereby possible tostart machining of the workpiece immediately. On the other hand, rapidtraversing the table at maximum speed may lead to heat generation of themotor. Since time is required to naturally cool the heat generation ofthe motor, it is desirable to avoid the heat generation. Therefore, itis suitable if possible to optimize the movement speed of the tableduring tool exchange.

A first aspect of the present disclosure relates to a control devicewhich controls a machine tool so as to move a table during exchange oftools, the control device including: a movement distance acquisitionunit which acquires a movement distance of the table during toolexchange; a movement time calculation unit which calculates a fastestmovement time from an acquired movement distance, and a speed at whichthe table is caused to move fastest; a tool exchange time calculationunit which calculates a tool exchange time; a comparison unit whichcompares the tool exchange time calculated and the fastest movement timecalculated; and a speed changing unit which changes the movement speedof the table, in a case of the fastest movement time being shorter thanthe tool exchange time, so that the movement time of the table becomeslonger than the fastest movement time.

In addition, a second aspect of the present invention relates to arecording medium encoded with a program for causing a computer tofunction as a control device which controls a machine tool so as to movea table during exchange of tools, the program causing the computer tofunction as: a movement distance acquisition unit which acquires amovement distance of the table during tool exchange; a movement timecalculation unit which calculates a fastest movement time from anacquired movement distance, and a speed at which causing the table tomove fastest; a tool exchange time calculation unit which calculates atool exchange time; a comparison unit which compares the tool exchangetime calculated and the fastest movement time calculated; and a speedchanging unit which changes the movement speed of the table, in a caseof the fastest movement time being shorter than the tool exchange time,so that the movement time of the table becomes longer than the fastestmovement time.

According to the present disclosure, it is possible to provide a controldevice and a recording medium encoded with a program which can optimizethe movement speed of a table during tool exchange.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram showing a machining systemincluding a control device according to a first embodiment of thepresent disclosure;

FIG. 2 is a block diagram showing the configuration of the controldevice of the first embodiment;

FIG. 3 is a flowchart showing the flow of operations of the controldevice of the first embodiment;

FIG. 4 is a conceptual diagram showing an example of changing the speedby the control device of the first embodiment; and

FIG. 5 is a conceptual diagram showing an example of changing the speedby a control device of a second embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a control device 1 and program according to each embodimentof the present disclosure will be explained with reference to FIGS. 1 to5. First, before explaining the control device 1 in each embodiment, asummary of the relationship between the exchange of a tool 21 of amachine tool 2 controlled by the control device 1 and movement of atable 22 will be explained.

The machine tool 2 is included in a machining system 100, as shown inFIG. 1. The machine tool 2 machines a work piece 24, while exchanging aplurality of tools 21 retained in a magazine 23, according to themachining contents. In the exchange of the tools 21, the time isrequired to mount the tool 21 retained in the magazine 23 to the spindle25, after removing the tool 21 mounted to a spindle 25 (hereinafterreferred to as tool exchange time). It is possible to shorten the cycletime (machining time), by moving the table 22 (workpiece 24) in advanceto the next machining position, during the tool exchange time. Forexample, in the case of moving the table 22, it is possible to positionthe table 22 at the destination in the shortest time, by moving eachaxis at the maximum speed according to the destination. On the otherhand, in the case of the tool exchange time being longer than theshortest time, it is possible to suppress heat generation of a motor(not shown) running the spindle, by changing (adjusting) the movementtime of the table 22. The control device 1 and program according to thefollowing embodiment suppress heat generation of a motor, i.e. achieveoptimization of the movement speed of the table 22, by changing themovement speed of the table 22.

First Embodiment

Next, the control device 1 and program according co the first embodimentof the present disclosure will be explained with reference to FIGS. 1 to4. The control device 1 is included in a machining system 100, as shownin FIG. 1. The control device 1 is configured to be able to control amachine tool 2. In the present embodiment, the control device 1 controlsthe machine tool 2 so as to move the table 22 during exchange of thetools 21. The control device 1 includes: a machining program storageunit 11, a detection unit 12, a movement distance acquisition unit 13, amovement time calculation unit 14, a tool exchange time calculation unit15, a comparison unit 16, a speed changing unit 17, and a controlexecution unit 18, as shown in FIG. 2.

The machining program storage unit 11 is a secondary storage medium suchas a hard dish, for example. The machining program storage unit 11stores a machining program indicating the movements of the tool 21 andtable 22. In addition, the machining program storage unit 11 storesvarious setting information such as the movement speed of the axes ofthe table 22, or retaining positions of tools 21 in the magazine 23.

The detection unit 12, for example, is realized by a CPU operation. Thedetection unit 12 detects commands for conducting tool exchange andmovement of the table 22 simultaneously, in relation to a machiningprogram stored in the machining program storage unit 11. The detectionunit 12 causes the movement distance acquisition unit 13 and toolexchange time calculation unit 15 to move according to the detection.

The movement distance acquisition unit 13 is realized by the CPUoperation, for example. The movement distance acquisition unit 13acquires the movement distance of the table 22 during tool exchange. Themovement distance acquisition unit 13 acquires the movement distances ofthe X axis and Y axis from the start to the end of tool exchange, fromthe machining program storage unit 11, for example. In addition, themovement distance acquisition unit 13 acquires the highest speed of eachof the X axis and Y axis, from the machining program storage unit 11.

The movement time calculation unit 14 is realized by a CPU operation,for example. The movement time calculation unit 14 calculates thefastest movement time, from the acquired movement distance, and thespeed at which the table 22 is caused to move fastest. The movement timecalculation unit 14, for example, calculates the fastest movement time,based on the movement distance, and the highest speed of each axis.

The tool exchange time calculation unit 15 is realized by a CPUoperation, for example. The tool exchange time calculation unit 15calculates the exchange time of the tools 21. The tool exchange timecalculation unit 15, for example, acquires the retaining position of thetools 21 in the magazine 23, from the machining program as settinginformation. The tool exchange time calculation unit 15 calculates thetool exchange time based on the retaining position of the acquired tool21.

The comparison unit 16 is realized by a CPU operation, for example. Thecomparison unit 16 compares the calculated tool exchange time with thecalculated fastest movement time. More specifically, the comparison unit16 compares whether the calculated tool exchange time is longer than thecalculated fastest movement time.

The speed chancing unit 17 is realized by a CPU operation, for example.In the case of the fastest movement time being shorter than the toolexchange time, the speed changing unit 17 changes the movement speed ofthe table 22, so that the movement time of the table 22 is longer thanthe fastest movement time, with the tool exchange time being made as thelimit. The speed changing unit 17, for example, recalculates therapid-traverse time constant of the X axis and Y axis, and changes themovement time during tool exchange to be longer. The speed changing unit17, for example, changes the movement speed of the table 22, so that themovement time becomes 95% relative to the tool exchange time.

The control execution unit 18 is realized by a CPU operation, forexample. The control execution unit 18 causes the table 22 to actuallymove at the changed movement speed of the table 22. In addition, thecontrol execution unit 18 causes the tool 21 to be exchanged inaccordance with the machining program.

Next, operation of the control device 1 of the present embodiment willbe explained using the flowchart of FIG. 3. First, the detection unit 12detects a command for simultaneously conducting tool exchange andmovement of the table 22, in relation to the machining program stored inthe machining program storage unit 11 (Step S1). The detection unit 12causes the movement distance acquisition unit 13 and tool exchange timecalculation unit 15 to operate, when detecting the correspondingcommand.

Next, the movement distance acquisition unit 13 acquires the movementdistance of the table 22 (Step S2). The movement distance acquisitionunit 13, for example, acquires the movement distance of the table 22included in the detected machining program.

Next, the movement time calculation unit 14 calculates the movement timefrom the movement distance of the table 22 and the fastest movementspeed of each axis (Step S3). Next, the tool exchange time calculationunit 15 calculates the exchange time of the tool 21 (Step S4).

Next, the comparison unit 16 compares the tool exchange time with themovement time of the table 22 (Step S5). In the case of the toolexchange time being longer than the movement time of the table 22 (StepS5: YES), the processing advances to Step S6. On the other hand, in thecase of the tool exchange time being shorter than the movement time ofthe table 22 (Step S5: NO), the processing advances to Step S7.

In Step S6, the speed changing unit 17 changes the movement speed of thetable 22. The speed changing unit 17, for example, changes so as to makethe movement speed of the table 22 longer, with the tool exchange timebeing made as a limit.

Next, in Step S7, the control execution unit 18 actually executes theexchange of tools 21 and the movement of the table 22. The processingaccording to the present flow thereby ends.

Next, the program of the present disclosure will be explained. Eachconfiguration included in the control device 1 can be realized by way ofhardware, software or a combination thereof. Herein, being realized bysoftware means being realized by a computer reading and executing aprogram.

The program can be stored using various types of non-transitory computerreadable media, and supplied to the computer. Non-transitory computerreadable medium includes various types of tangible storage media.Examples of non-transitory computer readable media include magneticrecording media (e.g., flexible disk, magnetic tape, hard disk drive),magneto-optical recording media (e.g., magneto-optical disk), CD-ROM(Read Only Memory), CD-R, CD-R/W and semiconductor memory (e.g., maskROM, PROM (programmable ROM), EPROM (Erasable PROM), flash ROM, RAM(random access memory)). In addition, the display program may besupplied to the computer by way of various types of transitory computerreadable media. Examples of transitory computer readable media includeelectrical signals, optical signals and electromagnetic waves.Transitory computer readable media can supply programs to the computervia wired communication paths such as electric wires and optical fiber,or wireless communication paths.

Next, Examples of the present embodiment will be explained withreference to FIG. 4. As shown in FIG. 4, the movement start time of thetable 22 and the tool exchange start time are denoted as t0. Then, theexchange end time of the tool 21 is denoted as t1. In the case of movingthe table 22 the fastest, the table 22 moves up to the target position,during the time from t0 to t2 (movement time TB1) (one-dot dashed lineM1 in FIG. 4). In contrast, in the case of delaying the movement speedof the table 22 according to the tool exchange time, the table 22 movesto the target position (two-dot dashed line M2 in FIG. 4), during thetime from t0 to t3 (movement time TB2). Herein, time t3 is later thantime t2, and earlier than t1. In the exchange end time of the tool 21(time t1), it is thereby possible to move the table 22 to the targetposition, and possible to slow the movement speed of the axis. It shouldbe noted that it is ideal for the movement of the table 22 to becompleted at the exchange end time t1 of the tool 21. Therefore, thetime t3 at which the movement of the table 22 is completed is preferablyset at a time close to time t1, while not being the same time as timet1. Compared to the case of being the same time, it is thereby possibleto give a margin in the machining of the workpiece 24.

According to the control device 1 and program in the first embodimentabove, the following effects are obtained. (1) The control device 1which controls the machine tool 2 so as to make the table 22 move duringexchange of the tools 21, includes: the movement distance acquisitionunit 13 which acquires the movement distance of the table 22 during toolexchange; the movement time calculation unit 14 which calculates thefastest movement time from the acquired movement distance and the speedat which the table 22 is caused to move the fastest; the tool exchangetool calculation unit 15 which calculates the exchange time of the tool21; the comparison unit 16 which compares the calculated tool exchangetime with the calculated fastest movement time; and the speed changingunit 17 which changes the movement speed of the table 22, in a case ofthe fastest movement time being shorter than the tool exchange time, sothat the movement time of the table 22 becomes longer than the fastestmovement time, with the tool exchange time being made as a limit. Inaddition, a program causes a computer to function as the control device1 which controls the machine tool so as to move the table 22 duringexchange of the tools 21, the computer being caused to function as: themovement distance acquisition unit 13 which acquires the movementdistance of the table 22 during tool exchange; the movement timecalculation unit 14 which calculates the fastest movement time from theacquired movement distance and the speed at which the table 22 is causedto move the fastest; the tool exchange tool calculation unit 15 whichcalculates the exchange time of the tool 21; the comparison unit 16which compares the calculated tool exchange time with the calculatedfastest movement time; and the speed changing unit 17 which changes themovement speed of the table 22, in a case of the fastest movement timebeing shorter than the tool exchange time, so that the movement time ofthe table 22 becomes longer than the fastest movement time, with thetool exchange time being made as a limit. It is thereby possible tochange the movement speed of the table 22 during the tool exchange.Therefore, it is possible to suppress heat generation of the axis movingthe table 22. In addition, it is possible to suppress electricalconsumption, and suppress operating costs. In other words, it ispossible to optimize the movement speed of the table 22.

Second Embodiment

Next, a control device 1 and program according to a second embodiment ofthe present disclosure will be explained with reference to FIG. 5. Uponexplanation of the second embodiment, the same reference symbols areassigned to constituent elements which are identical to theaforementioned embodiment, and explanations thereof are omitted orabbreviated. The control device 1 and program according to The secondembodiment are made taking consideration of the movement time of a brakemechanism (clamping, unclamping operation) of the axis, in addition tothe control device 1 and program in the first embodiment.

More specifically, the control device 1 and program according to thesecond embodiment differ from the first embodiment in that the movementtime calculation unit 14 adds the clamping time and unclamping time ofthe table 22 to the fastest movement time to calculate the actualmovement time. In addition, the control device 1 and program accordingto the second embodiment differ from the first embodiment, in that thespeed changing unit 17 changes the movement speed of the table 22 inorder to make the actual movement time of the table 22 longer than thefastest movement time, with the tool exchange time being made as alimit, in the case of the actual movement time being shorter than thetool exchange time.

Next, Examples of the control device 1 and program according to thesecond embodiment will be explained with reference to FIG. 5. As shownin FIG. 5, the movement start time of the table 22 and the tool exchangestart time are denoted as t1. Then, the exchange end time of the tool 21is denoted as t1. In the case of moving the table 22 at the fastestspeed, the table 22 moves up to the target position from time t0 to timet7 (movement time TB1) (one-dot dashed line M3 in FIG. 5). At this time,the actual movement time TB1 is comprised of the unclamping time TD2(end time t4), movement time TC1 (end time t6), and clamping time TD1(end time t7).

In contrast, in the case of slowing the movement speed of the table 22according to the tool exchange time, the table 22 moves to the targetposition (two-dot dashed line M4 in FIG. 5) from time t0 to time t3(movement time TB2). At this time, the actual movement time TB2 isconfigured by the unclamping time TD2 (end time t4), movement time TC2(end time t5), and clamping time TD1 (end time t3). Herein, time t3 islater than time t7, and earlier than time t1. At the exchange end timeof the tool 21 (time t1), it is thereby possible to make the table 22move to the target position, and slow the movement speed of the axis.

According to the control device 1 and program in the second embodimentabove, the following effects are obtained. (3) The movement timecalculation unit 14 adds the clamping time and unclamping time of thetable 22 to the fastest movement time to calculate the actual movementspeed. Even if being an axis having a brake mechanism, it is therebypossible to realize a change in speed. Therefore, it is possible toimprove the versatility of the control device 1.

(4) The speed changing unit 17, in the case of the actual movement timebeing shorter than the tool exchange time, changes the movement speed ofthe table 22, so that the actual movement time of the table 22 becomeslonger than the fastest movement time, with the tool exchange time beingmade as a limit. It is thereby possible to improve the versatility ofthe control device 1, by changing the actual speed.

Although the respective preferred embodiments of the control device andprogram of the present disclosure have been explained above, the presentdisclosure is not to be limited to the aforementioned embodiments, andmodifications are possible as appropriate. For example, in the aboveembodiments, the speed changing unit 17 may store the changed movementspeed of the table 22 as an item among the various settings in themachining program storage unit 11. The control execution unit 18 may beconfigured so as to control movement of the table 22, by reading astored item, upon executing a machining program.

In addition, in the above embodiments, the speed changing unit 17 is notlimited to a change in speed, and may be configured so as to change theacceleration of the axis. In addition, the speed changing unit 17 may beconfigured so as to change the movement speed of the table 22, byadopting the time constant of the speed by a sequence decided inadvance.

In addition, in the above embodiments, the control device 1 is explainedas being independent from the machine tool 2; however, it is not limitedthereto. The control device 1 may be configured integrally with themachine tool 2.

EXPLANATION OF REFERENCE NUMERALS

-   1 control device-   2 machine tool-   13 movement distance acquisition unit-   14 movement time calculation unit-   15 tool exchange time calculation unit-   16 comparison unit-   17 speed changing unit-   21 tool-   22 table

What is claimed is:
 1. A control device which controls a machine tool so as to move a table during exchange of tools, the control device comprising: a movement distance acquisition unit which acquires a movement distance of the table during tool exchange; a movement time calculation unit which calculates a fastest movement time from an acquired movement distance, and a speed at which the table is caused to move fastest; a tool exchange time calculation unit which calculates a tool exchange time; a comparison unit which compares the tool exchange time calculated with the fastest movement time calculated; and a speed changing unit which changes the movement speed of the table, in a case of the fastest movement time being shorter than the tool exchange time, so that the movement time of the table becomes longer than the fastest movement time.
 2. The control device according to claim 1, wherein the movement time calculation unit adds a clamping time and an unclamping time of the table to the fastest movement time to calculate an actual movement time.
 3. The control device according to claim 2, wherein the speed changing unit, in a case of the actual movement time being shorter than the tool exchange time, changes the movement speed of the table, so that the actual movement time of the table becomes longer than the fastest movement time, with the tool exchange time being made as a limit.
 4. A recording medium encoded with a program which causes a computes to function as a control device that controls a machine tool so as to cause a table to move during exchange of tools, the program causing the computer to function as: a movement distance acquisition unit which acquires a movement distance of the table during tool exchange; a movement time calculation unit which calculates a fastest movement time from as acquired movement distance, and a speed at which the table is caused to move fastest; a tool exchange time calculation unit which calculates a tool exchange time; a comparison unit which compares the tool exchange time calculated with the fastest movement time calculated; and a speed changing unit which changes the movement speed of the table, in a case of the fastest movement time being shorter than the tool exchange time, so that the movement time of the table becomes longer than the fastest movement time. 